Benchmark: isFunction vs typeof function 6

HTML Preparation code:

<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.core.js"></script>

Script Preparation code:

window.sample = function () {};
window.$isFunction = function (v) { return typeof v === 'function'; };

Tests:

isFunction
var isfunc = _.isFunction(sample);
typeof function
var isfunc = typeof sample === 'function';
instanceof
var isfunc = sample instanceof Function;
wrapped typeof function (like optimized _.isFunction)
var isfunc = $isFunction(sample);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
isFunction
typeof function
instanceof
wrapped typeof function (like optimized _.isFunction)

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Windows

View result in a separate tab

Test name	Executions per second
isFunction	42723464.0 Ops/sec
typeof function	130899288.0 Ops/sec
instanceof	105848112.0 Ops/sec
wrapped typeof function (like optimized _.isFunction)	131643336.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**Benchmark Definition**
The benchmark is designed to compare four different approaches for checking if an object or value is a function in JavaScript:

1. `typeof function`
2. `isFunction` (a custom implementation)
3. `instanceof Function`

**Options Compared**

* `typeof function`: uses the built-in `typeof` operator with the string `'function'`.
* `$isFunction`: a custom implementation of the `isFunction` function, which checks if a value is a function using the `typeof` operator.
* `instanceof Function`: uses the `instanceof` operator to check if an object is an instance of the `Function` constructor.

**Pros and Cons**

* `typeof function`:
	+ Pros: widely supported, fast (in most cases).
	+ Cons: may not work correctly in older browsers or with certain types of values (e.g., functions with no name).
* `$isFunction`: similar to `typeof function`, but implemented as a custom function.
	+ Pros: provides more control over the implementation and can handle edge cases better.
	+ Cons: requires additional code and may not be as fast as the built-in `typeof` operator.
* `instanceof Function`:
	+ Pros: explicit and clear way to check if an object is a function, works in most browsers.
	+ Cons: slower than `typeof function`, may require more computational resources.

**Library Used**
The benchmark uses Lodash (version 4.17.5) as a dependency. Specifically, it imports the `_.isFunction` function from Lodash.

**Special JS Feature/Syntax**
There is no special JavaScript feature or syntax used in this benchmark. The tests only involve basic JavaScript operations and functions.

**Other Alternatives**

* Other approaches to check if an object is a function include using the `Function.isFunction()` method (introduced in ECMAScript 5) or creating a custom implementation similar to `$isFunction`.
* Additionally, some JavaScript engines, such as V8 (used by Chrome), have their own built-in optimizations for checking if an object is a function. However, these optimizations are not typically exposed through the standard API.

In summary, this benchmark provides a simple and controlled way to compare different approaches to checking if an object or value is a function in JavaScript, highlighting the trade-offs between using the built-in `typeof` operator, a custom implementation like `$isFunction`, and the `instanceof` operator.

Related benchmarks:

isFunction vs typeof function 6 (version: 0)

isFunction vs typeof function

Comparing performance of: isFunction vs typeof function vs instanceof vs wrapped typeof function (like optimized _.isFunction)

Created: 6 years ago by: Guest

Jump to the latest result

isFunction

typeof function

instanceof

wrapped typeof function (like optimized _.isFunction)

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):